1. Field of the Invention
The present invention relates to a window unit.
2. Description of the Related Art
In locations such as hospitals, it is known to have doors with window units that contain a mechanism allowing vision through the window to be temporarily obscured and so provide privacy. One such type of window unit comprises a pair of static outer panes and a slidable third pane sandwiched between the outer pair. The third pane and one of the outer panes are each provided with a series of horizontal opaque stripes. The third pane is manually moveable (by a cam mechanism) between an open position and a closed position. In the open position, its opaque stripes are aligned with those of the outer pane to allow viewing through the window. In the closed position, its opaque stripes are aligned with transparent stripes of the outer pane to prevent viewing through the window.
One problem with this arrangement is that weight of the third pane limits the size (i.e. height and width) of the window unit that may practically be produced or operated manually.
A second problem relates to the limited proportion of the “open” area of the window. i.e. the area of the window through which a person may see is limited. Ideally, the whole of the window area of the window unit would be transparent when the unit is in its open configuration. However, for such an application it is necessary to provide an overlap of the two sets of opaque stripes in order to ensure privacy when the window unit is in its closed configuration. Consequently, the proportion of the window area that is “open” is less than 50%.